The present invention relates to an image forming system provided with a humidifying apparatus and the sheet humidifying apparatus for giving water to a sheet.
As the image formation by an electro-photographic process is well-known, an image is formed by a process by which a toner image is formed by the charge, exposure and development, the formed toner image is transferred onto the sheet, the toner image transferred onto the sheet is fixed.
In the fixing process in this process, it is conducted that the toner is fused by the heat and pressure, and the image is fixed on the sheet, however, at the time of that, the phenomenon that the water content is evaporated from the sheet by the heat, is generated. Further, when the sheet is exposed to the outside air after the fixing, the phenomenon that the sheet absorbs the water content from the outside air, is generated.
Because such an evaporation of the water content and an absorption of the water content occur at a different ratio on the front and rear surface of the sheet, there is a problem that the surging or curl is easily generated in the sheet.
The phenomenon that the concave and convex are formed in the sheet S as shown in FIG. 1(a), is called as the surging, and the phenomenon that the sheet S is curved in the one direction as shown in FIGS. 1(b), (c), is called as the curl.
For these phenomena, in each processing conducted on the sheet after image formation, because the problem which is the cause of trouble in the sheet conveyance or, processing, in the bookbinding process, a problem that the quality of the product completed by the image formation and after-processing like that a bulky booklet is formed is lowered, a problem that sheets delivered from the apparatus are not uniform, and the integration is difficult are occurred, a counter-measure for the surging and the curl is necessary.
In Tokkaihei (Unexamined Japanese Patent Publication) No 4-338060, a humidifying apparatus by which the water vapor is blown to the sheet is proposed, a humidifying apparatus using the humidification roller from a point in which the control of the water supply amount is excellent, the influence on the vicinity of humidifying apparatus by the water vapor is small, the apparatus can be made compact, noticed, and this kind of humidifying apparatus is considered, and a humidifying apparatus by which in U.S. Pat. No. 5,895,154, Tokkai No. 2006-8282, the water is supplied from the water supply tank to the humidification roller, and the sheet is humidified, is disclosed.
In the humidifying apparatus, the electrical equipment such as a motor for the sheet conveyance, a solenoid for driving the gate for switching the conveyance path, DC power source which is the power source for them, control substrate, each kind of switch, is provided, however, because the humidifying apparatus accommodates the water for the humidification, and there is a possibility that the water content is affixed to the electrical parts, and their performance is lowered, or the accident such as electrical leaking is generated, it is necessary to protect the electrical parts from the water.
In the processing apparatus using the ordinary water, the protection section by which the electrical parts are protected from the water vapor is used, however, in the sheet humidifying apparatus using the humidification roller, in the water supply tank for supplying the water to the humidification roller, because the structure in which the free water surface is in contact with the outside air is used, only the water proof for the water vapor, is not enough, a counter measure to protect that the water is splashed from the free water surface by the vibration, and affixed to the electrical parts, is necessary.